Where any considerable amount of cement is to be used the contractor will find that it will pay to erect a small bag house or to close off a room at the mixing plant. Provide the enclosure with a locked door and with a small window into which the bags are required to be thrown as fast as emptied. One trustworthy man is given the key and the task of counting up the empty bags each day to see that they check with the bags of cement used. The following rule for packing and shipping is given by Gilbreth.[A]
[A] "Field System," Frank B. Gilbreth. Myron C. Clark Publishing Co., New York and Chicago.
"Pack cement bags laid flat, one on top of the other, in piles of 50. They can then be counted easily. Freight must be prepaid when cement bags are returned and bills of lading must be obtained in duplicate or credit cannot be obtained on shipment."
The volumes given above are for cement compacted in the barrel. When the cement is emptied and shoveled into boxes it measures from 20 to 30 per cent more than when packed in the barrel. The following table compiled from tests made for the Boston Transit Commission, Mr. Howard Carson, Chief Engineer, in 1896, shows the variation in volume of cement measured loose and packed in barrels:
| Brand | Vol. Barrel cu. ft. | Vol. Packed cu. ft. | Vol. Loose cu. ft. | Per cent Increase in bulk |
| Portland. | ||||
| Giant | 3.5 | 3.35 | 4.17 | 25 |
| Atlas | 3.45 | 3.21 | 3.75 | 18 |
| Saylors | 3.25 | 3.15 | 4.05 | 30 |
| Alsen | 3.22 | 3.16 | 4.19 | 33 |
| Dyckerhoff | 3.12 | 3.03 | 4.00 | 33 |
Mr. Clarence M. Foster is authority for the statement that Utica cement barrels measure 16¼ ins. across at the heads, 19½ ins. across the bilge, and 25¾ ins. in length under heads, and contain 3.77 cu. ft. When 265 lbs. of Utica natural hydraulic cement are packed in a barrel it fills it within 2½ ins. of the top and occupies 3.45 cu. ft., and this is therefore the volume of a barrel of Utica hydraulic cement packed tight.
In comparative tests made of the weights and volumes of various brands of cements at Chicago in 1903, the following figures were secured:
| Vol. per bbl., cu. ft. | Weight per bbl., lbs. | Weight per cu. ft. | ||
| Brand. | Loose. | Gross. | Net. | Loose, lbs. |
| Dyckerhoff | 4.47 | 395 | 369.5 | 83 |
| Atlas | 4.45 | 401 | 381 | 85.5 |
| Alpha | 4.37 | 400.5 | 381 | 86.5 |
| Puzzolan | 4.84 | 375 | 353.5 | 73.5 |
| Steel | 4.96 | 345 | 322.5 | 67.5 |
| Hilton | 4.64 | 393 | 370.5 | 79.5 |
SPECIFICATIONS AND TESTING—The great bulk of cement used in construction work is bought on specification. The various government bureaus, state and city works departments, railway companies, and most public service corporations have their own specifications. Standard specifications are also put forward by several of the national engineering societies, and one of these or the personal specification of the engineer is used for individual works. Buying cement to specification necessitates testing to determine that the material purchased meets the specified requirements. For a complete discussion of the methods of conducting such tests the reader is referred to "Practical Cement Testing" by W. Purves Taylor.
According to this authority a field testing laboratory will cost for equipment $250 to $350. Such a laboratory can be operated by two or three men at a salary charge of from $100 to $200 per month. Two men will test on an average four samples per day and each additional man will test four more samples. The cost of testing will range from $3 to $5 per sample, which is roughly equivalent to 3 cts. per barrel of cement, or from 3 to 5 cts. per cubic yard of concrete. These figures are for field laboratory work reasonably well conducted under ordinarily favorable conditions. In large laboratories the cost per sample will run somewhat lower.